Extracellular Vesicles Derived from Acidified Metastatic Melanoma Cells Stimulate Growth, Migration, and Stemness of Normal Keratinocytes

Maxim L Bychkov,Ekaterina N Lyukmanova,Alexander S Paramonov,Evgeny V Yastremsky,Mikhail P Kirpichnikov,Mikhail A Shulepko,Irina N Mikhaylova,Artem V Kirichenko

doi:10.3390/biomedicines10030660

Abstract

Metastatic melanoma is a highly malignant tumor. Melanoma cells release extracellular vesicles (EVs), which contribute to the growth, metastasis, and malignancy of neighboring cells by transfer of tumor-promoting miRNAs, mRNA, and proteins. Melanoma microenvironment acidification promotes tumor progression and determines EVs’ properties. We studied the influence of EVs derived from metastatic melanoma cells cultivated at acidic (6.5) and normal (7.4) pH on the morphology and homeostasis of normal keratinocytes. Acidification of metastatic melanoma environment made EVs more prooncogenic with increased expression of prooncogenic mi221 RNA, stemless factor CD133, and pro-migration factor SNAI1, as well as with downregulated antitumor mir7 RNA. Incubation with EVs stimulated growth and migration both of metastatic melanoma cells and keratinocytes and changed the morphology of keratinocytes to stem-like phenotype, which was confirmed by increased expression of the stemness factors KLF and CD133. Activation of the AKT/mTOR and ERK signaling pathways and increased expression of epidermal growth factor receptor EGFR and SNAI1 were detected in keratinocytes upon incubation with EVs. Moreover, EVs reduced the production of different cytokines (IL6, IL10, and IL12) and adhesion factors (sICAM-1, sICAM-3, sPecam-1, and sCD40L) usually secreted by keratinocytes to control melanoma progression. Bioinformatic analysis revealed the correlation between decreased expression of these secreted factors and worse survival prognosis for patients with metastatic melanoma. Altogether, our data mean that metastatic melanoma EVs are important players in the transformation of normal keratinocytes.

Highlights

Metastatic melanoma is a highly malignant tumor whose therapy is hampered by inflammatory, hypoxic, and acidic milieu promoting tumor growth and invasion [1,2]
We found that extracellular vesicles (EVs) derived from the culture media of metastatic melanoma cells cultivated at pH 6.5 (“acidified” EVs) demonstrate a higher content of the factors involved in melanoma progression than EVs derived from the culture media of the same cells cultivated at pH 7.4 (“normal” EVs)
We revealed that EVs derived from acidified cells contained EGFR, vascular endothelial growth factor A (VEGFA), ITGA3, ITGV, and heat shock protein 60 (HSP60) mRNAs (Table 1), which code the surface receptors, secreted factors, and migration messengers implicated in the control of cell growth and migration [26,44–47]

Summary

Introduction

Metastatic melanoma is a highly malignant tumor whose therapy is hampered by inflammatory, hypoxic, and acidic milieu promoting tumor growth and invasion [1,2]. Both melanoma growth and metastasis are regulated by intrinsic cellular mechanisms, such as the PI3K/AKT/mTOR pathway [3], and by cross-talk between melanoma. Biomedicines 2022, 10, 660 cells, neighboring cells, and extracellular matrix (ECM) by means of extracellular vesicles (EVs) [4]. EVs, which cancer cells release among other factors remodeling the cell microenvironment [8,9]), can transfer between the cells tumor-promoting microRNAs (miRNAs), mRNA, and even proteins [10–13]. Cancer EVs inhibit tumor immunosurveillance [10,11], stimulate angiogenesis [14], mediate drug resistance of tumor cells [15,16], and promote malignant transformation of neighboring epithelial cells [17] and fibroblasts [18].

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